1. Field of the Invention
This invention pertains in its preferred embodiment to a semiconductor wafer enclosed minimum volume fluidic cushion transport system interconnecting a multiplicity of processing stations or tools whereby any individual wafer can be randomly directed into and from a multiplicity of processing apparatus tools which are associated with said transport system. Said enclosed systems have controlled atmosphere and maintained in said condition throughout the system whereby individual wafers move in a programmed sequence from processing station to processing station without the intervention of human hands.
2. Description of the Prior Art
Prior to the current practice and trends of making semiconductor devices of greater and greater densities where more complicated and complex processing techniques are required, wafers were processed utilizing the batch technique whereby said wafers were essentially hand carried from processing station to processing station usually contained in separate rooms some of which required special atmospheric control which in turn made it necessary for the human operators to wear special uniforms and other forms of clothing. These conditions increased the cost of manufacturing semiconductor component parts as well as making product yield enhancement difficult and complex.
The art has taught sectorized processing sections wherein a central conveyor system transports wafer slices to any desired sector which may have one or a series of processing units or tools associated with a particular sector representing one serialized set of process steps comprising one mask level of processing. These sectors have preprogrammed sensing means which upon sensing the presence of a wafer at its entry port accepts same for processing. This type of arrangement uses a conveyor belt or an air cushion conveyor means or any other conveying means to transport wafers from processor to processor. Likewise a central taxi system usually an overhead type apparatus is employed to carry the wafer from sector to sector. The conveyors and processing apparatus are usually housed in "clean room" with open conveyor systems. This concept is more particularly illustrated by U.S. Pat. Nos. 3,889,355 and 2,678,237.
In a system of the type indicated above where work pieces are transported from process unit to process unit in accordance with a prescribed sequence corresponding to the processing requirements for the work piece is controlled and more particularly illustrated in U.S. Pat. No. 3,845,286.
Air cushion transport means utilizing vacuum means to stop or hold semiconductor wafers and subsequently position same is shown in U.S. Pat. No. 3,717,381.